Italy striker Antonio Cassano has left troubled Serie A club Parma after rescinding his contract.
Huddersfield striker Martin Paterson has joined Orlando City on loan until the end of the season.
Goalkeeper Jason Brown has left Aberdeen with immediate effect.
The Wales international made 28 appearances for the Dons after arriving from Blackburn 18 months ago, but has been unable to displace Jamie Langfield his season.
Pittodrie chief executive Duncan Fraser told the club's official website: "Jason made it clear to us he was keen to return to England and continue his career.
"He is a proud member of the Welsh international team and in order to maintain his place in the squad he feels it is vital for him to be playing every week.
"The club wish Jason all the best with his future career."